Electromechanical relays are switching devices typically used to control high power devices. Such relays generally comprise two primary components: a movable conductive cantilever and an inductive element, generally an electromagnetic coil. When activated, the electromagnetic coil exerts a magnetic force on the beam in the same way that a magnet will pick up a nail. This causes the beam to be pulled toward the coil, down onto an electrical contact, closing the relay by creating an electrical connection. Said electrical connection may be galvanic or more often based on a capacity variation. The more important the capacity is, the more it will enable a current having a given frequency crossing the switching device. These micro-electromechanical relays have been down-sized in order to fit the needs of modern electronic systems. The micro-electromechanical relays do not present limitations observed for solid-state relays that require large and expensive heat sinks as resistances of such devices on ON and OFF position are generally one order of magnitude higher than for electromechanical switches and cause a strong heating effect.
For example, the document U.S. Pat. No. 6,094,116 proposes an improved micro-electromagnetic switching device. The structure proposed in this document allows a unique powerless hold feature. A magnetic layer is first deposited on the substrate. An electromagnetic coil is then created adjacent to this material. A deflectable structure in a magnetic material is then laid down in order to have a portion over or adjacent to at least one electrical contact. In operation, current passes through the coil, causing the deflectable structure to deflect, and either make or break contact with the electrical contacts.
This implementation of an electromechanical switch offers a good miniaturization but it requires the deposition of a magnetic material and requires specific current or voltages to switch from one position to the other.